XML markup injection via multiline QName validation bypass
Published Sep 1, 2026 · Updated Sep 1, 2026
XML injection in @xmldom/xmldom 0.9.0 through 0.9.11 allows remote attackers to inject markup through malformed XML names. The shared reg() builder gives the anchored QName_exact expression the multiline flag, so creation APIs validate only a well-formed first line and retain unconstrained trailing text. Exploitation requires an application to place attacker-controlled names into the affected DOM creation APIs and serialize the resulting nodes, enabling XML structure modification or downstream XSS.
Summary
What happened
XML injection in @xmldom/xmldom 0.9.0 through 0.9.11 allows remote attackers to inject markup through malformed XML names. The shared reg() builder gives the anchored QName_exact expression the multiline flag, so creation APIs validate only a well-formed first line and retain unconstrained trailing text. Exploitation requires an application to place attacker-controlled names into the affected DOM creation APIs and serialize the resulting nodes, enabling XML structure modification or downstream XSS.
The record
- CVE
- CVE-2026-83609
- Published
- Sep 1, 2026
- Updated
- Sep 1, 2026
- Vendor
- xmldom
- Product
- xmldom
- Classifications
- CWE-91, CWE-625
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 1, 2026CVE publishedPublication date reported by the CVE source.
- Sep 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 0.9.0, < 0.9.12
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream creation-time QName validation proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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